Ultrahigh frequency and microwave relaxation of lithium perchlorate in tetrahydrofuran

Abstract

The complex permittivity of 0.05 M L1CIO4 in tetrahydrofuran (THF) at 25°in the frequency range 0.3-8.5GHz has been measured. An admittance bridge was used in the frequency range 0.3-1.5 GHz and a power reflection method in the range 2-8.5 GHz. The real and imaginary parts of the permittivity follow a Cole-Davidson distribution of relaxation times with an average relaxation frequency /r = 1.5 GHz and a distribution parameter ß = 0.8. Including data reported in the literature the relaxation amplitude «o -of the solute is found to be a linear function of the concentration of ion pairs. The Cole-Davidson distribution parameter, ß, is calculated by a modified Glarum theory which postulates that the diffusion-controlled collision between ion-pair dipoles couples with the diffusional rotational relaxation. The calculated value of ß approximates the experimental distribution parameters including those for LiC104-THF-benzene mixtures.

The critical role of configurational flexibility in facilitating reversible reactive metal deposition from borohydride solutions

“…long-range electrostatics), may affect the various cluster equilibria differently, which we plan to investigate in upcoming work. To test whether the presence of dipolar clusters could facilitate formation of ionic species at high concentration through permittivity increases, as previously observed in other strongly associating electrolytes, 32,[40][41][44][45][46] we conducted simulations to determine the influence of several proposed clusters on the solution dielectric constant (supplementary information, Figure S6). The computed lowest free energy electrolyte structure, THF3Ca(BH4)2, possesses a bent geometry and a calculated dipole moment of 5 Debye.…”

Characterization of Tetrahydrofuran as a Solvent for Proton Transfer Reactions

“…If the overall reaction involves no unforeseen components so that it can be characterized by the following three reactions: B + HA ~ BH+A -, BH+A -~ BH + + A-, and BH § + S ~ B + SH § the titration curve should obey asH+ = KaBH + KaBHA p / ( I OO-P )[ A -] [11] where P is percent titrated. If the overall reaction involves no unforeseen components so that it can be characterized by the following three reactions: B + HA ~ BH+A -, BH+A -~ BH + + A-, and BH § + S ~ B + SH § the titration curve should obey asH+ = KaBH + KaBHA p / ( I OO-P )[ A -] [11] where P is percent titrated.…”

“…The formation of contact and solvent separated ion pairs could be distinguished (2). In some cases the conductivity data could be supplemented by ultrasonic relaxation measurements, providing information on the dynamics of the association processes (6,7,11).…”

Ion Pairing and Redissociaton in Low-Permittivity Electrolytes for Multivalent Battery Applications

“…We hypothesize that the interplay between ion pairing and molar conductivity can be rationalized via a phenomenon termed redissociation . − In low-permittivity electrolytes, associated salt species tend to form as a result of the strong electrostatic interactions compared with polar solvents . If these associated species are endowed with a significant dipole moment, they will increase the total permittivity via an increase in the orientational polarizability and favor a larger population of dissociated salt species, i.e., redissociation, as the concentration increases. ,, Previous studies of the interplay between permittivity increase and ion association have focused on monovalent salts. ,− ,− To the best of our knowledge, redissociation has not been analyzed or proposed for nonaqueous multivalent systems, despite the inherently stronger electrostatic interactions present.…”

“…While previous work on combined permittivity and speciation diagrams have used a posteriori experimental data, ,, the current MSM is entirely theoretically and computationally based and relies on experimental data only for validation. Furthermore, a significant number of dielectric relaxation studies have been carried out on low-permittivity monovalent systems ,,, as well as some high-permittivity multivalent systems, but to date none have been carried out on low-permittivity multivalent electrolytes, the subject of the present work.…”